# Filtering Data

**URL:** <https://community.wolfram.com/t/filtering-data/2162>\
**Category:** Questions\
**Tags:** signal-processing, mathematica\
**Created:** [May 9, 2014, 12:36am UTC](https://community.wolfram.com/t/filtering-data/2162 "2014-05-09T00:36:56Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![sproubi1](https://avatars.discourse-cdn.com/v4/letter/s/73ab20/32.png) [@sproubi1](https://community.wolfram.com/u/sproubi1)\
**Post date:** [May 9, 2014, 12:36am UTC](https://community.wolfram.com/t/filtering-data/2162/1 "2014-05-09T00:36:56Z")

</div>

I have taken a DFT of some data points I called “v” which was a 193 data points.

```auto
a = Fourier[{v}, FourierParameters -> {1, 1}];

```

The Fourier returned a 193 data points. As it turned out, I don’t need all of them. In the output, how can tell Mathematica to index points 90 to a 105 to be 0? In other words, instead of having to painstakingly count and find out which points are between 90 and 105, Mathematica does it automatically sets them to 0.

Thank you in advance.

---

<div class="post-metadata">

**Author:** ![girishav](https://yyz1.discourse-cdn.com/wolfram/user_avatar/community.wolfram.com/girishav/32/28159_2.png) [@girishav](https://community.wolfram.com/u/girishav)\
**Post date:** [May 9, 2014, 1:45am UTC](https://community.wolfram.com/t/filtering-data/2162/2 "2014-05-09T01:45:44Z")

</div>

You can write-

```auto
In[4]:= b = ReplaceList[Take[a[[1]], {90, 105}], {x __,___ } -> 0]

Out[4]= {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}

```

And then,

```auto
Join[Take[a[[1]], 89], b, Take[a[[1]], {106, 193}]]

```

to get the list.